# Electrostatic rod homework

1. Sep 30, 2008

### MIA6

1. A body will maintain a constant negative electrostatic charge if the body
1) Maintains the same excess of electrons. 3) Continuously receives more electrons than it loses.
I chose 3) but I think both choices work. However, the correct answer is 1), I don’t why 3) is wrong.

2. Negatively charged rod A is used to charge rod B by induction. Object C is then charged by direct contact with rod B. The charge on object C
1) is positive 3) is negative.
I chose 3) because when negative charged rod A moves close to one end of rod B, the electrons in rod B would gather at the other end, so left the opposite end all positive. After that, when C comes to contact with rod B, it depends on which end it touches. I am little confused. If it touches the negative end, then C becomes negative; vice versa. But the answer was 1).

thanks for help.

2. Sep 30, 2008

### LowlyPion

Re: electrostatic

1. The operative word is Constant. Unchanging. Stays the same.

2. If B's charge is affected by induction, it will be net positive and then it will be a sink for electrons when it is touched by C, imparting a net positive to C as well.

3. Oct 1, 2008

### MIA6

Re: electrostatic

But induction is not conduction, why B will be net positive? If B is positive orginally, it's still postive; if it's negative, it will still be negative.

4. Oct 1, 2008

### LowlyPion

Re: electrostatic

A is negative. Induction makes B net positive. Touching neutral C to B makes C net positive too.

5. Oct 2, 2008

### MIA6

Re: electrostatic

If B is net positive, where did some electrons in B go?